SEPRAD - Workshop


Linking Solar Eruptions to Space Radiation Storms: Solar Energetic Particle Events and Flares foretold


Athanasios Papaioannou
National Observatory of Athens, Penteli, Greece


Solar eruptions, such as solar flares (SFs) and coronal mass ejections (CMEs) are the primary drivers of space
radiation storms. A key element for the decoding of such storms is the establishment of empirical statistical relations between their characteristics and the observed properties of their parent solar events. These attempt to unfold patterns and relationships, using all observational evidence at hand, which in turn point to the underlying physical processes of the generation of space radiation storms [1].

We report on new data driven statistical methods that have been developed for the identification of the likelihood
of Solar Energetic Particle (SEP) event occurrence and their expected characteristics. These methods are based on precursor information of SFs [forecasting mode] and on actual data of SFs, CMEs and radio bursts [nowcasting mode]. A reductive statistical method for the SEP probability of occurrence has been implemented, using as input SF information. It makes use of, either, the expected full disk probability [forecasting mode] or of the location (longitude) and the size (maximum soft X-ray [SXR] intensity) of the flare [nowcasting mode] [2].

Moreover, employing CME parameters (velocity and angular width), proper functions per width (i.e. halo, partial
halo, non-halo) have been identified. In addition, using as input the SXR and radio fluence, another (non-operational) algorithm for the probability of SEP occurrence, based on the ESPERTA concept [3], has been implemented.

We demonstrate the validation of each method using categorical scores constructed on archived data and we further present independent case studies [4].


[1] Papaioannou et al., Solar flares, Coronal Mass Ejections and Solar Energetic Particle Event Characteristics, J. Space Weather and Space Clim., 6, A42, DOI: 10.1051/swsc/2016035, 2016
[2] Papaioannou et al., A Novel Forecasting System for Solar Particle Events and Flares (FORSPEF),
J. Phys.: Conf. Ser., 632, 012075, 2015.
[3] Alberti et al., Solar Activity from 2006 to 2014 and Short-term Forecasts of Solar Proton Events Using the
ESPERTA Model, Astrophys. J. 838.1 (59), 2017.
[4] Anastasiadis et al., Predicting Flares and Solar Energetic Particle Events: the FORSPEF tool, Solar Phys.,
DOI 10.1007/s11207-017-1163-7, 2017


Part of this research was supported through the ESA Contracts No.4000109641/13/NL/AK „Improvement of Solar Particle Events and Flare Prediction“ and No. 4000120480/17/NL/LF/hh „Solar Energetic Particle (SEP) Advanced Warning System (SAWS)“.